All language subtitles for 9. Introduction to Backend VS Frontend

How is Node most often used, we can use it for scripts that do things on our computer.

Our local machine, for example, to read and write files.

But in the majority of cases, we use Node to create servers to build web and mobile applications that

connect to databases, provide user data and things like videos, photos and other content.

And our servers also provide security features like allowing users to log in in order to understand

how we'll be applying what we learn in the next few videos, including when we apply in our final project.

We need to get a bit of a lesson in backhands technology and how it compares to the front end.

Now, if you're already familiar with working with backends from frontend development or working with

backends in other runtimes and programming languages, this might be review, but we need to make sure

we have our fundamentals in place when it comes to the web and even mobile.

There's usually this idea of a client and a server.

The front end and the back end.

The front end.

Here is your browser or mobile phone.

It's what you see on the screen as a user.

The backend is what happens behind the scenes where we tend to have things like security features,

input validation and most of our business logic, especially if it's something like intellectual property

that's core to our products and we want to be in full control over it.

For example, business logic like how Google determines the ranking of websites when you search this

top secret algorithm that's so important to how Google works and on the back end, we tend to talk to

multiple different servers providing services that we then put together in some meaningful way for our

application.

Let's think about this from the top.

What happens when I load a website like Google.com?

I'm telling my browser here.

Go find Google.com and it's going to go where Google has their servers for the front page of Google.

And it's going to make what we call a request and say, Hey server, can you give me some data for whatever

is on that page?

It could be the Google logo, the header or the search bar.

The server will then send back what we call a response and say, OK, here's the data that you need

to display this page.

This can include static files like HTML, which is the hypertext markup language used to lay the page

out and, for example, separate the logo from the search bar.

We might have JavaScript, which we use to perform actions on that page or CSC to provide the visual

styling and appearance of that page.

The language that these server uses to talk to the clients and the language that the client uses to

send requests for data to the server is called FTP or the Hypertext Transfer Protocol.

HDP is used to transfer these files from the server to the browser.

And oftentimes we'll see HDP s, which is the secure version of this protocol, where all communication

between the client and server is encrypted to help keep our data secure.

In case someone tries to come between us in the browser and the server to snoop on what we're seeing.

Spy on us and steal our data.

Thankfully, most websites use the secure version of HTP by default now to make sure our data is secure

when it's being transferred over the internet, so there's nothing suspicious going on here.

All right.

Let's say we load facebook.com instead, and we have a page that's more dynamic.

We might ask the server, Hey, I just logged in.

Can you give me the data for my user and the data for my friends and the server is going to say no problem?

Here it is.

But rather than sending that data in files that are static like we saw before, it could send the data

back in a number of formats.

The data could be JSON or XML, or even just plain text data.

Where Jason is our JavaScript object format or JavaScript object notation using our curly braces and

key value pairs, just like in JavaScript and an alternative format is XML, which looks a lot like

HTML, where we use these pairs of tags.

And for example, here in our correct version, a pair of tags can have some data.

That's what the back end is for.

It serves us the data that we need on the front end on the client side to show something useful to the

user.

So how are backhands made?

We can use any language and runtime that you want.

You can use node, but also Python or Ruby Java or the Go programming language.

And when we write code in those languages to serve our data to the front end, we call our code backend

code.

Now you might be asking, why do we need the server to send us data at all?

Why don't we just keep the data in the front end and do everything there?

Well, on the server, we do things that we can't or shouldn't do on the browser, things like security,

logging our users in and input validation where the client can send us data that we don't expect and

we need to make sure that it matches our needs.

This idea of a client server architecture that we just talked about is used by most of the web, and

building out that server side is what most node applications are built to do.

Our front end is almost always written in some form of HTML, CSS and JavaScript.

But the backend can be in nearly any programming language node allows us developers the huge advantage

of programming the backend and frontend in the same language, and it provides dozens of other benefits

that we're going to be talking about throughout the course.

So let's get to it.

I'll see you in the next video.